Commit e0dc0d8f4a327d033bfb63d43f113d5f31d11b3c
Committed by
Linus Torvalds
Linus Torvalds
1 parent
2ca48ed5cc
Exists in
master
and in
4 other branches
[PATCH] add vm_insert_pfn()
Add a vm_insert_pfn helper, so that ->fault handlers can have nopfn functionality by installing their own pte and returning NULL. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Showing 2 changed files with 47 additions and 0 deletions Side-by-side Diff
include/linux/mm.h
| ... | ... | @@ -1124,6 +1124,8 @@ |
| 1124 | 1124 | int remap_pfn_range(struct vm_area_struct *, unsigned long addr, |
| 1125 | 1125 | unsigned long pfn, unsigned long size, pgprot_t); |
| 1126 | 1126 | int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); |
| 1127 | +int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, | |
| 1128 | + unsigned long pfn); | |
| 1127 | 1129 | |
| 1128 | 1130 | struct page *follow_page(struct vm_area_struct *, unsigned long address, |
| 1129 | 1131 | unsigned int foll_flags); |
mm/memory.c
| ... | ... | @@ -1277,6 +1277,51 @@ |
| 1277 | 1277 | } |
| 1278 | 1278 | EXPORT_SYMBOL(vm_insert_page); |
| 1279 | 1279 | |
| 1280 | +/** | |
| 1281 | + * vm_insert_pfn - insert single pfn into user vma | |
| 1282 | + * @vma: user vma to map to | |
| 1283 | + * @addr: target user address of this page | |
| 1284 | + * @pfn: source kernel pfn | |
| 1285 | + * | |
| 1286 | + * Similar to vm_inert_page, this allows drivers to insert individual pages | |
| 1287 | + * they've allocated into a user vma. Same comments apply. | |
| 1288 | + * | |
| 1289 | + * This function should only be called from a vm_ops->fault handler, and | |
| 1290 | + * in that case the handler should return NULL. | |
| 1291 | + */ | |
| 1292 | +int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, | |
| 1293 | + unsigned long pfn) | |
| 1294 | +{ | |
| 1295 | + struct mm_struct *mm = vma->vm_mm; | |
| 1296 | + int retval; | |
| 1297 | + pte_t *pte, entry; | |
| 1298 | + spinlock_t *ptl; | |
| 1299 | + | |
| 1300 | + BUG_ON(!(vma->vm_flags & VM_PFNMAP)); | |
| 1301 | + BUG_ON(is_cow_mapping(vma->vm_flags)); | |
| 1302 | + | |
| 1303 | + retval = -ENOMEM; | |
| 1304 | + pte = get_locked_pte(mm, addr, &ptl); | |
| 1305 | + if (!pte) | |
| 1306 | + goto out; | |
| 1307 | + retval = -EBUSY; | |
| 1308 | + if (!pte_none(*pte)) | |
| 1309 | + goto out_unlock; | |
| 1310 | + | |
| 1311 | + /* Ok, finally just insert the thing.. */ | |
| 1312 | + entry = pfn_pte(pfn, vma->vm_page_prot); | |
| 1313 | + set_pte_at(mm, addr, pte, entry); | |
| 1314 | + update_mmu_cache(vma, addr, entry); | |
| 1315 | + | |
| 1316 | + retval = 0; | |
| 1317 | +out_unlock: | |
| 1318 | + pte_unmap_unlock(pte, ptl); | |
| 1319 | + | |
| 1320 | +out: | |
| 1321 | + return retval; | |
| 1322 | +} | |
| 1323 | +EXPORT_SYMBOL(vm_insert_pfn); | |
| 1324 | + | |
| 1280 | 1325 | /* |
| 1281 | 1326 | * maps a range of physical memory into the requested pages. the old |
| 1282 | 1327 | * mappings are removed. any references to nonexistent pages results |